Cadence-based selection, playback, and transition between song versions

ABSTRACT

A system and methods for acquiring cadence and selecting a song version based on the acquired cadence are disclosed. If the system detects a new cadence, then a new song version that corresponds to the new cadence can be played. The new song version playback can start in a corresponding position as the location of playback in a currently-playing song version. Each related song version shares one or more characteristics, such as melody, but is different in at least one characteristic, such as tempo.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Ser. No. 62/163,882 filed onMay 19, 2015 and entitled CADENCE-BASED SELECTION, PLAYBACK, ANDTRANSITION BETWEEN SONG VERSIONS, the disclosure of which is herebyincorporated by reference in its entirety.

BACKGROUND

Running, as well as many other recreational or fitness activities,include repetitive motions. For example, running and walking involverepetitive steps, biking involves repetitive rotational movements,rowing involves repetitive strokes, and swimming involves repetitivestrokes and kicks. There are of course many other recreation and fitnessactivities that also include various repetitive motions. Theserepetitive motion activities may be performed in place (e.g., using atreadmill, stationary bike, rowing machine, swimming machine, etc.) orin motion (e.g., on roads, trails, or tracks or in a pool or body ofwater, etc.). Cadence refers to the frequency of these repetitivemotions and is often measured in terms of motions per minute (e.g.,steps per minute, rotations per minute, strokes per minute, or kicks perminute).

Many people enjoy consuming media content, such as listening to audiocontent or watching video content, while running or engaging in otherrepetitive-motion activities. Examples of audio content include songs,albums, podcasts, etc. Examples of video content include movies, musicvideos, television episodes, audiobooks, etc. Using a mobile phone orother media-playback device a person can access large catalogs of mediacontent. For example, a user can access an almost limitless catalog ofmedia content through various free and subscription-based streamingservices. Additionally, a user can store a large catalog of mediacontent on his or her mobile device.

This nearly limitless access to media content introduces new challengesfor users. For example, it may be difficult to find or select the rightmedia content that complements a particular moment during a run or otherrepetitive-motion activity.

SUMMARY

In general terms, this disclosure is directed to transitioning betweensong versions based on an acquired cadence of a repetitive activity. Inone aspect, a computer readable data storage device storing instructionsis disclosed. The instructions, when executed by at least one processingdevice, can include causing a media-playback device to: acquire a firstcadence, initiate playback of a first song version selected from aplurality of related song versions, where the selection of the firstsong version is based on the first cadence; acquire a second cadence,and initiate playback of a second song version selected from theplurality of related song versions, where the selection of the secondsong version is based on the second cadence. The first song version andthe second song version share at least one characteristic. Each of theplurality of related song versions is different from each of the otherplurality of related song versions in at least one characteristic.

In a second aspect, a method for transitioning from a first song versionto a second song version is disclosed. The method includes acquiring afirst cadence, selecting a first song version that corresponds to thefirst cadence, streaming the first song version, acquiring a secondcadence, selecting a second song version that corresponds to the secondcadence, and streaming the second song version.

In a third aspect, a media server is disclosed. The media server caninclude a database including at least one computer readable data storagedevice, including a plurality of song versions, where each of theplurality of song versions has a different tempo than each of the othersong versions. Also, the at least one computer readable data storagedevice can include instructions stored thereon which, when executed byat least one processing device, cause the media server to: receive afirst request to begin streaming a first song version, where the firstsong version has a first tempo, enable streaming of a first songversion, receive a second request to begin streaming a second songversion, where the second song version has a second tempo, and enablestreaming of the second song version, where the first tempo and thesecond tempo are different by at least about 5 beats per minute.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example system for cadence determination and mediacontent selection.

FIG. 2 is a schematic illustration of the example system of FIG. 1.

FIG. 3 illustrates an example method for selecting a song version andfor playing and transitioning between different versions of a song.

FIG. 4 is a schematic illustration of three versions of a song.

FIG. 5 illustrates an example method for determining a playback positionfor a next song version.

FIG. 6 illustrates an example method for composing a plurality of songversions.

FIG. 7 illustrates an example cadence-acquiring device of FIG. 2.

FIG. 8 illustrates an example method of determining cadence performed bysome embodiments of the cadence-determination engine of FIG. 2.

FIG. 9 shows an example series of filtered sample measurements from theaccelerometer of FIG. 7.

FIG. 10 shows the example series of filtered sample measurements of FIG.9 with additional annotations to identify portions of the signal thatare used in analyzing the periodicity of the repetitive motion.

DETAILED DESCRIPTION

Various embodiments will be described in detail with reference to thedrawings, wherein like reference numerals represent like parts andassemblies throughout the several views. Reference to variousembodiments does not limit the scope of the claims attached hereto.Additionally, any examples set forth in this specification are notintended to be limiting and merely set forth some of the many possibleembodiments for the appended claims.

Users of media-playback devices often consume media content whileengaging in various activities, including repetitive motion activities.As noted above, examples of repetitive-motion activities may includeswimming, biking, running, rowing, and other activities. Consuming mediacontent may include one or more of listening to audio content, watchingvideo content, or consuming other types of media content. For ease ofexplanation, the embodiments described in this application are presentedusing specific examples. For example, audio content (and in particularmusic) is described as an example of one form of media consumption. Asanother example, running is described as one example of arepetitive-motion activity. However, it should be understood that thesame concepts are equally applicable to other forms of media consumptionand to other forms of repetitive-motion activities, and at least someembodiments include other forms of media consumption and/or other formsof repetitive-motion activities.

The users may desire that the media content fits well with theparticular repetitive activity. For example, a user who is running maydesire to listen to music with a beat that corresponds to the user'scadence. Beneficially, by matching the beat of the music to the cadence,the user's performance or enjoyment of the repetitive-motion activitymay be enhanced. This desire cannot be met with traditionalmedia-playback devices and media-delivery systems.

FIG. 1 illustrates an example system 100 for cadence determination andmedia content selection. The example system 100 includes amedia-playback device 102 and a media-delivery system 104. The system100 communicates across a network 106. Also shown is a user U who isrunning. The user U's upcoming steps S are shown as well. A steprepresents a single strike of the runner's foot upon the ground.

The media-playback device 102 operates to play media content items toproduce media output 110. In some embodiments, the media content itemsare provided by the media-delivery system 104 and transmitted to themedia-playback device using the network 106. A media content item is anitem of media content, including audio, video, or other types of mediacontent, which may be stored in any format suitable for storing mediacontent. Non-limiting examples of media content items include songs,albums, music videos, movies, television episodes, podcasts, other typesof audio or video content, and portions or combinations thereof.

The media-playback device 102 plays media content for the user based onthe user's cadence. In the example shown, the media output 110 includesmusic with a tempo that corresponds to the user's cadence. The tempo (orrhythm) of music refers to the frequency of the beat and is typicallymeasured in beats per minute (BPM). The beat is the basic unit of rhythmin a musical composition (as determined by the time signature of themusic). Accordingly, in the example shown, the user U's steps occur atthe same frequency as the beat of the music.

For example, if the user U is running at a cadence of 180 steps perminute, the media-playback device 102 may play a media content itemhaving a tempo equal to or approximately equal to 180 BPM. In otherembodiments, the media-playback device 102 plays a media content itemhaving a tempo equal or approximately equal to the result of dividingthe cadence by an integer such as a tempo that is equal to orapproximately equal to one-half (e.g., 90 BPM when the user is runningat a cadence of 180 steps per minute), one-fourth, or one-eighth of thecadence. Alternatively, the media-playback device 102 plays a mediacontent item having a tempo that is equal or approximately equal to aninteger multiple (e.g., 2×, 4×, etc.) of the cadence. Further, in someembodiments, the media-playback device 102 operates to play multiplemedia content items including one or more media content items having atempo equal to or approximately equal to the cadence and one or moremedia content items have a tempo equal or approximately equal to theresult of multiplying or dividing the cadence by an integer. Variousother combinations are possible as well.

In some embodiments, the media-playback device 102 operates to playmusic having a tempo that is within a predetermined range of a targettempo. In at least some embodiments, the predetermined range is plus orminus 2.5 BPM. For example, if the user U is running at a cadence of 180steps per minute, the media-playback device 102 operates to play musichaving a tempo of 177.5-182.5 BPM. Alternatively, in other embodiments,the predetermined range is itself in a range from 1 BPM to 10 BPM.

Further, in some embodiments, the media-playback device 102 operates toplay music having a tempo equal to or approximately equal to a user U'scadence after it is rounded. For example, the cadence may be rounded tothe nearest multiple of 2.5, 5, or 10 and then the media-playback device102 plays music having a tempo equal to or approximately equal to therounded cadence. In yet other embodiments, the media-playback device 102uses the cadence to select a predetermined tempo range of music forplayback. For example, if the user U's cadence is 181 steps per minute,the media-playback device 102 may operate to play music from apredetermined tempo range of 180-184.9 BPM; while if the user U'scadence is 178 steps per minute, the media-playback device 102 mayoperate to play music from a predetermined tempo range of 175-179.9 BPM.

FIG. 2 is a schematic illustration of an example system 100 for cadencedetermination and media content selection. In FIG. 2, the media-playbackdevice 102, the media-delivery system 104, and the network 106 areshown. Also shown are the user U and a satellite S.

As noted above, the media-playback device 102 operates to play mediacontent items. In some embodiments, the media-playback device 102operates to play media content items that are provided (e.g., streamed,transmitted, etc.) by a system external to the media-playback devicesuch as the media-delivery system 104, another system, or a peer device.Alternatively, in some embodiments, the media-playback device 102operates to play media content items stored locally on themedia-playback device 102. Further, in at least some embodiments, themedia-playback device 102 operates to play media content items that arestored locally as well as media content items provided by other systems.

In some embodiments, the media-playback device 102 is a computingdevice, handheld entertainment device, smartphone, tablet, watch,wearable device, or any other type of device capable of playing mediacontent. In yet other embodiments, the media-playback device 102 is alaptop computer, desktop computer, television, gaming console, set-topbox, network appliance, blue-ray or DVD player, media player, stereo, orradio.

In at least some embodiments, the media-playback device 102 includes alocation-determining device 150, a touch screen 152, a processing device154, a memory device 156, a content output device 158, acadence-acquiring device 160, and a network access device 162. Otherembodiments may include additional, different, or fewer components. Forexample, some embodiments may include a recording device such as amicrophone or camera that operates to record audio or video content. Asanother example, some embodiments do not include one or more of thelocation-determining device 150 and touch screen 152.

The location-determining device 150 is a device that determines thelocation of the media-playback device 102. In some embodiments, thelocation-determining device 150 uses one or more of the followingtechnologies: Global Positioning System (GPS) technology which mayreceive GPS signals 170 from satellites S, cellular triangulationtechnology, network-based location identification technology, Wi-Fipositioning systems technology, and combinations thereof.

The touch screen 152 operates to receive an input 172 from a selector(e.g., a finger, stylus etc.) controlled by the user U. In someembodiments, the touch screen 152 operates as both a display device anda user input device. In some embodiments, the touch screen 152 detectsinputs based on one or both of touches and near-touches. In someembodiments, the touch screen 152 displays a user interface 164 forinteracting with the media-playback device 102. As noted above, someembodiments do not include a touch screen 152. Some embodiments includea display device and one or more separate user interface device.Further, some embodiments do not include a display device.

In some embodiments, the processing device 154 comprises one or morecentral processing units (CPU). In other embodiments, the processingdevice 154 additionally or alternatively includes one or more digitalsignal processors, field-programmable gate arrays, or other electroniccircuits.

The memory device 156 operates to store data and instructions. In someembodiments, the memory device 156 stores instructions for amedia-playback engine 166 that includes a same song transition engine168. In some embodiments, the media-playback engine 166 operates toplayback media content and the same song transition engine 168 operatesto select media content for playback based on a cadence.

The memory device 156 typically includes at least some form ofcomputer-readable media. Computer readable media includes any availablemedia that can be accessed by the media-playback device 102. By way ofexample, computer-readable media include computer readable storage mediaand computer readable communication media.

Computer readable storage media includes volatile and nonvolatile,removable and non-removable media implemented in any device configuredto store information such as computer readable instructions, datastructures, program modules, or other data. Computer readable storagemedia includes, but is not limited to, random access memory, read onlymemory, electrically erasable programmable read only memory, flashmemory and other memory technology, compact disc read only memory, blueray discs, digital versatile discs or other optical storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, or any other medium that can be used to store thedesired information and that can be accessed by the media-playbackdevice 102. In some embodiments, computer readable storage media isnon-transitory computer readable storage media.

Computer readable communication media typically embodies computerreadable instructions, data structures, program modules or other data ina modulated data signal such as a carrier wave or other transportmechanism and includes any information delivery media. The term“modulated data signal” refers to a signal that has one or more of itscharacteristics set or changed in such a manner as to encode informationin the signal. By way of example, computer readable communication mediaincludes wired media such as a wired network or direct-wired connection,and wireless media such as acoustic, radio frequency, infrared, andother wireless media. Combinations of any of the above are also includedwithin the scope of computer readable media.

The content output device 158 operates to output media content. In someembodiments, the content output device 158 generates media output 110for the user U. Examples of the content output device 158 include aspeaker, an audio output jack, a Bluetooth transmitter, a display panel,and a video output jack. Other embodiments are possible as well. Forexample, the content output device 158 may transmit a signal through theaudio output jack or Bluetooth transmitter that can be used to reproducean audio signal by a connected or paired device such as headphones or aspeaker.

The cadence-acquiring device 160 operates to acquire a cadenceassociated with the user U. In at least some embodiments, thecadence-acquiring device 160 operates to determine cadence directly andincludes one or more accelerometers or other motion-detectingtechnologies. Alternatively, the cadence-acquiring device 160 operatesto receive data representing a cadence associated with the user U. Forexample, in some embodiments, the cadence-acquiring device 160 operatesto receive data from a watch, bracelet, foot pod, chest strap, shoeinsert, anklet, smart sock, bicycle computer, exercise equipment (e.g.,treadmill, rowing machine, stationary cycle), or other device fordetermining or measuring cadence. Further, in some embodiments, thecadence-acquiring device 160 operates to receive a cadence value inputby the user U or another person.

The network access device 162 operates to communicate with othercomputing devices over one or more networks, such as the network 106.Examples of the network access device include wired network interfacesand wireless network interfaces. Wireless network interfaces includesinfrared, BLUETOOTH® wireless technology, 802.11a/b/g/n/ac, and cellularor other radio frequency interfaces in at least some possibleembodiments.

The network 106 is an electronic communication network that facilitatescommunication between the media-playback device 102 and themedia-delivery system 104. An electronic communication network includesa set of computing devices and links between the computing devices. Thecomputing devices in the network use the links to enable communicationamong the computing devices in the network. The network 106 can includerouters, switches, mobile access points, bridges, hubs, intrusiondetection devices, storage devices, standalone server devices, bladeserver devices, sensors, desktop computers, firewall devices, laptopcomputers, handheld computers, mobile telephones, and other types ofcomputing devices.

In various embodiments, the network 106 includes various types of links.For example, the network 106 can include wired and/or wireless links,including Bluetooth, ultra-wideband (UWB), 802.11, ZigBee, cellular, andother types of wireless links. Furthermore, in various embodiments, thenetwork 106 is implemented at various scales. For example, the network106 can be implemented as one or more local area networks (LANs),metropolitan area networks, subnets, wide area networks (such as theInternet), or can be implemented at another scale. Further, in someembodiments, the network 106 includes multiple networks, which may be ofthe same type or of multiple different types.

The media-delivery system 104 comprises one or more computing devicesand operates to provide media content items to the media-playbackdevices 102 and, in some embodiments, other media-playback devices aswell. The media-delivery system 104 includes a media server 180 and arepetitive-motion activity server 182. In at least some embodiments, themedia server 180 and the repetitive-motion activity server 182 areprovided by separate computing devices. In other embodiments, the mediaserver 180 and the repetitive-motion activity server 182 are provided bythe same computing devices. Further, in some embodiments, one or both ofthe media server 180 and the repetitive-motion activity server 182 areprovided by multiple computing devices. For example, the media server180 and the repetitive-motion activity server 182 may be provided bymultiple redundant servers located in multiple geographic locations.

The media server 180 operates to transmit stream media 218 tomedia-playback devices such as the media-playback device 102. In someembodiments, the media server 180 includes a media server application184, a processing device 186, a memory device 188, and a network accessdevice 190. The processing device 186, memory device 188, and networkaccess device 190 may be similar to the processing device 154, memorydevice 156, and network access device 162 respectively, which have eachbeen previously described.

In some embodiments, the media server application 184 operates to streammusic or other audio, video, or other forms of media content. The mediaserver application 184 includes a media stream service 194, a media datastore 196, and a media application interface 198. The media streamservice 194 operates to buffer media content such as media content 206,208, and 210, for streaming to one or more streams 200, 202, and 204.

The media application interface 198 can receive requests or othercommunication from media-playback devices or other systems, to retrievemedia content items from the media server 180. For example, in FIG. 2,the media application interface 198 receives communication 232 from themedia-playback engine 166.

In some embodiments, the media data store 196 stores media content items210, media content metadata 212, and playlists 214. The media data store196 may comprise one or more databases and file systems. Otherembodiments are possible as well. As noted above, the media contentitems 210 may be audio, video, or any other type of media content, whichmay be stored in any format for storing media content.

The media content metadata 212 operates to provide various informationassociated with the media content items 210. In some embodiments, themedia content metadata includes one or more of title, artist name, albumname, length, genre, mood, era, etc. The playlists 214 operate toidentify one or more of the media content items 210 and. In someembodiments, the playlists 214 identify a group of the media contentitems 210 in a particular order. In other embodiments, the playlists 214merely identify a group of the media content items 210 withoutspecifying a particular order. Some, but not necessarily all, of themedia content items 210 included in a playlist 214 are associated with acommon characteristic such as a common genre, mood, or era.

The repetitive-motion activity server 182 operates to providerepetitive-motion activity-specific information about media contentitems to media-playback devices. In some embodiments, therepetitive-motion activity server 182 includes a repetitive-motionactivity server application 220, a processing device 222, a memorydevice 224, and a network access device 226. The processing device 222,memory device 224, and network access device 226 may be similar to theprocessing device 154, memory device 156, and network access device 162respectively, which have each been previously described.

In some embodiments, repetitive-motion activity server application 220operates to transmit information about the suitability of one or moremedia content items for playback during a particular repetitive-motionactivity. The repetitive-motion activity server application 220 includesa repetitive-motion activity interface 228 and a repetitive-motionactivity media metadata store 230.

In some embodiments, the repetitive-motion activity server application220 may provide a list of media content items at a particular tempo to amedia-playback device in response to a request that includes aparticular cadence value. Further, in some embodiments, the mediacontent items included in the returned list will be particularlyrelevant for the repetitive motion activity in which the user is engaged(for example, if the user is running, the returned list of media contentitems may include only media content items that have been identified asbeing highly runnable).

The repetitive-motion activity interface 228 operates to receiverequests or other communication from media-playback devices or othersystems, to retrieve information about media content items from therepetitive-motion activity server 182. For example, in FIG. 2, therepetitive-motion activity interface 228 receives communication 234 fromthe media-playback engine 166.

In some embodiments, the repetitive-motion activity media metadata store230 stores repetitive-motion activity media metadata 232. Therepetitive-motion activity media metadata store 230 may comprise one ormore databases and file systems. Other embodiments are possible as well.

The repetitive-motion activity media metadata 232 operates to providevarious information associated with media content items, such as themedia content items 210. In some embodiments, the repetitive-motionactivity media metadata 232 provides information that may be useful forselecting media content items for playback during a repetitive-motionactivity. For example, in some embodiments, the repetitive-motionactivity media metadata 232 stores runnability scores for media contentitems that corresponds to the suitability of particular media contentitems for playback during running. As another example, in someembodiments, the repetitive-motion activity media metadata 232 storestimestamps (e.g., start and end points) that identify portions of amedia content items that are particularly well-suited for playbackduring running (or another repetitive-motion activity).

Each of the media-playback device 102 and the media-delivery system 104can include additional physical computer or hardware resources. In atleast some embodiments, the media-playback device 102 communicates withthe media-delivery system 104 via the network 106.

Although in FIG. 2 only a single media-playback device 102 andmedia-delivery system 104 are shown, in accordance with someembodiments, the media-delivery system 104 can support the simultaneoususe of multiple media-playback devices, and the media-playback devicecan simultaneously access media content from multiple media-deliverysystems. Additionally, although FIG. 2 illustrates a streaming mediabased system for cadence determination and media content selection,other embodiments are possible as well. For example, in someembodiments, the media-playback device 102 includes a media data store196 and the media-playback device 102 is configured to perform cadencedetermination and media content selection without accessing themedia-delivery system 104. Further in some embodiments, themedia-playback device 102 operates to store previously streamed mediacontent items in a local media data store.

In at least some embodiments, the media-delivery system 104 can be usedto stream, progressively download, or otherwise communicate music, otheraudio, video, or other forms of media content items to themedia-playback device 102 based on a cadence acquired by thecadence-acquiring device 160 of the media-playback device 102. Inaccordance with an embodiment, a user U can direct the input 172 to theuser interface 164 to issue requests, for example, to play a selectedlocation-based playlist on the media-playback device 102 or to tag amedia content item with location data.

FIG. 3 is a block diagram of an example method 400 for playing andtransitioning between different versions of a song. The example method400 includes acquiring a cadence (operation 402), selecting a songversion (operation 404), streaming a song version (operation 406),acquiring a new cadence (operation 408), selecting a song version(operation 410), determining a playback position (operation 412),streaming a new song version (operation 414), and transitioning a newsong version (operation 416). The example method 400 can begin with auser selecting a particular song, a song type, a genre, a mood, a tempo,etc., in an operation that is not shown. Other embodiments may includemore or fewer operations.

The example method 400 begins by acquiring a cadence (operation 402)associated with a repetitive-motion activity of the user. Inembodiments, the cadence is acquired by determining the cadence based onmovements of the media-playback device 102 (e.g., using the methodsillustrated and described below with reference to at least FIGS. 7-10).In other embodiments, the cadence is acquired from a separate device,from a user input, or otherwise. Regardless of how the cadence isacquired, once that cadence is acquired, the example method 400 proceedsto operation 404.

After acquiring the cadence (operation 402), a song version is selected(operation 404). As used herein, “song” means a melody, set of melodies,theme, or set of themes for a musical composition. As used herein, a“song version” is one particular arrangement of the song. Inembodiments, each song version of a particular song shares the samemelody. FIG. 4 illustrates an example of three song versions. FIG. 6,discussed below, illustrates an example method for composing a pluralityof song versions.

FIG. 4 illustrates an example of three song versions 301, 302 and 303.In other embodiments, the song has more or fewer song versions. For onesong, each song version is about 3 minutes to about 60 minutes; about 5minutes; about 10 minutes; about 15 minutes; about 20 minutes; about 25minutes; about 30 minutes; about 40 minutes; about 45 minutes; about 50minutes; about 55 minutes; or about 60 minutes in length. Other songdurations are possible.

Each song version includes an arrangement of one or more musical parts.Examples of parts include: strings, woodwinds, horns (also termed brassinstruments), percussion, drums, vocals, etc. Each part can have one ormore sub-parts. For example, horns may include trumpet, trombone, Frenchhorn, tuba, etc.

Each song version can be arranged for a particular tempo and beperformed at a range of tempos. In the example shown in FIG. 4, thefirst song version 301 is composed at 140 beats per minute (bpm), thesecond song version 302 is composed at 160 bpm, and the third songversion 303 is composed at 175 bpm. In other embodiments, differenttempos are possible.

Each song version can be performed at different tempos that are greaterthan or lesser than the composed tempo. For example, the first songversion 301, composed at 140 bpm in example 300, can be performed at 130bpm, 135 bpm, 140 bpm, 145 bpm, 150 bpm, 155 bpm, and others. Also, asan example, the second song version 302, composed at 160 bpm in example300, can be performed at 150 bpm, 155 bpm, 160 bpm, 165 bpm, 170 bpm,and others. Additionally, as an example, the third song version 303,composed at 175 bpm, can be performed at 170 bpm, 175 bpm, 180 bpm, 185bpm, 190 bpm, and others.

In some embodiments, the arrangements and parts are different betweenvarious versions of one song. For example, the percussion arrangementprepared at 140 bpm might be difficult to play or sound rushed at 190bpm. Thus, as an example, sixteenth notes in the 140 bpm song versionmay be re-written as eighth notes in the 190 bpm song version. Othermodifications for any or all of the parts arrangements are possible.

In some embodiments, the faster song versions may include more bars inthe composition. As an example, take a song version written in 4/4 timeto be performed at 140 bpm and is 30 minutes long. That song version has4200 total beats and 1050 bars. When that same song version is performedat 190 bpm, the performance takes just over 22 minutes. In someembodiments, the song version lengths are all within about one to aboutthree minutes of each other. Thus, the song versions written at fastertempos may include one or more codas, additional bars of music not inthe slower tempo song versions, and/or other ways to make the songlengths more comparable.

In the illustrated example, each song version 301, 302 and 303 isdivided into one or more chapters. For a given song, each song version301, 302, and 303 has the same number of chapters. The examples in FIG.4 each have three chapters 310, 312, and 314. However, any number ofchapters may be used, for example, 2 chapters, 3 chapters, 4 chapters, 5chapters, 6 chapters, 7 chapters, 8 chapters, 9 chapters, 10 chapters,etc.

The chapters for a given song version can be stored together in a singlefile with annotations and/or time stamps that identify the beginning andend of chapters. Alternatively, the chapters for a given song versioncan be stored in separate files.

In embodiments, the chapters 310, 312, and 314 are further divided intosegments. The segments can correspond to changes in the arrangements,such as a dynamics changes like a crescendo, diminuendo, or energychanges, etc.

In the example illustrated in FIG. 4, song version 301 has a firstchapter that is 9 minutes long, a second chapter that is 10 minuteslong, and a third chapter that is 11 minutes long. Thus, song version301 is 30 minutes in its entirety. Song version 302 has a first chapterthat is 10 minutes long, a second chapter that is 10 minutes, 20 secondslong and a third chapter that is 11 minutes long. Thus, song version 302is 31 minutes and 20 seconds in its entirety. Song version 303 has afirst chapter that is 8 minutes long, a second chapter that is 9 minuteslong, and a third chapter that is 10 minutes long. Thus song version 303is 27 minutes long.

As shown in this example, each song version has a different length butthe same number of chapters. Also, the same chapter in different songversions can have the same length, such as the third chapter 314 in songversions 301 and 302, or different lengths, such as the first chapter310 in song versions 301 and 302.

Returning to operation 404 of FIG. 3, the tempo of the selected songversion is the same or nearly the same as the acquired cadence. Forexample, if a cadence of 179 repetitions per minute is acquired, then asong version with a tempo of about 180 beats per minute is selected inoperation 404. Generally, the tempo of the selected song version iswithin about 5 beats per minute of the acquired cadence.

When the version of the song is identified, a request is made to streamthe selected song version (operation 406). In an alternate embodiment,the media playback device can operate in an offline mode, and playbackof the song version is initiated from song versions stored locally. Asshown in FIG. 2, a media-playback device 102 can stream media 218 over anetwork 106 from a media server 180, where the media 218 stored on themedia server 180 includes a plurality of song versions for a pluralityof songs. In embodiments where the user selects the initial tempo of thesong, or selects their running cadence, the example method 400 beginswith operation 406. The media playback device starts playback of thesong version at the beginning of the song, however, a user can modifythe starting location of the song version playback.

After streaming the song version (operation 406), the cadence ismonitored. In embodiments, the cadence is monitored by continuing todetect the cadence associated with a repetitive movement of themedia-playback device 102. In other embodiments, the cadence ismonitored by continuing to acquire a cadence from a separate device, auser input, or otherwise.

A new cadence may be acquired in operation 408 that is different fromthe initially-acquired cadence in operation 402. The cadence can beacquired from measurement components in the media-playback device or anexternal sensor or sensors that are in communication with themedia-playback device. If a new cadence is acquired, then a new songversion is selected in operation 410.

Not all changes in cadence will result in the selection of a new songversion in operation 410. In embodiments, the cadence is determined tohave changed when the acquired cadence is different than the currentcadence by more than a predetermined threshold. Additionally, inembodiments, the cadence is determined to change when the acquiredcadence is different than the current cadence for at least apredetermined duration, which can be measured in terms of time, numberof steps, or other metrics. The predetermined threshold andpredetermined duration can be selected to distinguish intentionalchanges in cadence from short-term, environment-caused changes.

For example, someone running in a city might stop temporarily at atraffic intersection, or cadence might change to traverse a staircase,etc. A minimum period of a new cadence can be required beforedetermining that the user has a new cadence. For instance, about 5seconds, about 10 seconds, about 25 seconds, about 30 seconds, about 45seconds, about 60 seconds, about 90 seconds, or about 120 seconds may berequired before the example method selects a new song version inoperation 410.

Similar to operation 404, in operation 410 a new song version isselected where the tempo of the song version is equal to orsubstantially equal to the acquired cadence. For example, if the newacquired cadence in operation 408 was 184 repetitions per minute, a songversion with about 184 beats per minute would be selected, such as asong version with 184 beats per minute or a song version with 185 beatsper minute.

In contrast to operations 404 and 406, after selecting the song versionin operation 410, a playback position is next determined in operation412. The playback position is determined to provide the user with anear-seamless transition from the previous song version to the currentsong version. Operation 412 is shown and described below with referenceto FIG. 5.

FIG. 5 illustrates an example determination of a playback position(operation 412). The example determination (operation 412) includesidentifying the current chapter (operation 450), identifying thepercentage of the chapter played (operation 452), identifying thecorresponding chapter (operation 454), identifying the correspondingpercentage (operation 456), determining a delay (operation 458), anddetermining any pitch changes (operation 460). Also shown is the inputto the example determination, select song version (operation 410), andthe operation following the example determination, stream new songversion (operation 414). Other embodiments can include more or feweroperations.

After a song version is selected (operation 410), the chapter of thecurrently-playing song version is identified (operation 450). Operation450 can include retrieving metadata, for example, chapters, duration ofthe song version, duration of the chapters, etc., about the songversions. Additionally, operation 450 can include retrieving metadatathat includes the relationship between related song versions.

For example, a playback position of the currently-playing song versionis 14:30, or fourteen minutes thirty seconds, and is in chapter 4. Asdiscussed above with reference to FIG. 4, each song version can includeone or more chapters and the chapters are consistent across songversions for a particular song.

Next, the percentage of the chapter played is identified (operation452). Using the example above, the playback position of thecurrently-playing song version is 14:30 and is in chapter four, whichstarted at 12:00 and ends at 16:30 in the song version. That is, thecurrent chapter is 4:30 in length and 2:30 have played, thus thepercentage of the chapter played is about 56%. In embodiments where thesong versions are not divided into chapters, the percentage of the songversion played is determined after operation 410, rather than thepercentage of the chapter (operation 452).

After determining the current chapter and percentage of the chapterplayed, a corresponding chapter (operation 454) and correspondingpercentage of the chapter (operation 456) are determined for the nextsong version. Using the example discussed with reference to operation450, the currently-playing song version is in chapter four. Thus, thecorresponding chapter for beginning playback of the next song version ischapter four.

Next, about 56% of chapter 4 has been played in the currently-playingsong version. Thus, playback of the next song version will begin atabout 56% of chapter 4 of the next song version. If the next songversion's chapter 4 starts at 11:00 and ends at 15:00, which is fourminutes in length, then playback will begin about two minutes andfourteen seconds into the fourth chapter, or at about 13:14 of theentire song version. This starting position might be modified dependingon any delay or cross-fading determination in operation 458.

Any delays to accommodate transitioning to the next song version aredetermined in operation 458. For example, any cross-fading times can beaccounted for during operation 458.

Also, the beats of the currently-playing song version and the next songversion can be aligned. As an example, an alignment includes anyadjustments to make the first beat of each measure in thecurrently-playing song version align with the first beat of each measurein the next song version. This alignment can include temporarilyadjusting the tempo of the currently-playing song version, the tempo ofthe next song version, or both, such that they match when the next songversion is streamed.

After determining the playback location of the next song version, anypitch changes are next determined (operation 460). For example, whentransitioning from a currently-playing song version at a tempo of 155bpm to a next song version at a tempo of 180 bpm, the pitch of the nextsong version is lowered during the cross-fading. This pitch change canpotentially correct any changes in pitch when the tempo of one or bothof the song versions is adjusted. After or during cross-fading, thepitch is increased again, for example, over about 0.5 second, about 1second, about 2 seconds, about 3 seconds, about 4 seconds, or about 5seconds until it is back at the original pitch. Alternatively, or incombination, the pitch of the currently-playing song version isincreased during cross-fading.

Returning to FIG. 3, when the next song version has been selected(operation 410) and a playback position has been determined (operation412), the next song version is streamed (operation 414). As discussedabove with reference to operation 406, the next song version is streamedfrom a media server or played from a local version.

Then the next song version is transitioned into playback (operation416). For example, the currently-playing song version is faded out atthe same time that the next song version is faded in, which is termed“cross-fading” herein. The cross-fading of the two song versions canoccur over about 0.5 second, about 1 second, about 2 seconds, about 3seconds, about 4 seconds, about 5 seconds, about 7 seconds, about 10seconds, about 15 seconds, about 20 seconds, or about 30 seconds. Othertransition types are possible.

Also, transitioning to the next song version (operation 416) can includea time period of adjusting the pitch of the next song version, adjustingthe pitch of the currently-playing song version, or both.

After transitioning to the new song version (operation 416), the examplemethod 400 returns to monitor for a newly-acquired cadence (operation408).

FIG. 6 illustrates an example method 600 for composing a plurality ofsong versions. The example method 600 includes preparing a melody(operation 602), adapting the melody for a first tempo (operation 604),preparing accompanying parts (operation 606), adapting the melody for asecond tempo (operation 608), preparing accompanying parts (operation610), adapting the melody for a third tempo (operation 612), preparingaccompanying parts (operation 614), and recording performances atvarious tempos (operation 616). Other embodiments can include more orfewer operations.

The example method 600 begins by preparing a melody (operation 602). Themelody can include sub-melodies or sub-parts, such as one or moreverses, one or more bridges, one or more refrains, one or more choruses,etc. In embodiments, preparing a melody (operation 602) is preparing themelody for a specific tempo, such as 160 bpm.

After the melody is prepared (operation 602), the melody is adapted forone or more tempos. In the example method 600, the melody is adapted forthree tempos: a first tempo (operation 604), a second tempo (operation608), and a third tempo (operation 612). Each of these is a differentsong version. In embodiments, the first tempo is 140 bpm, the secondtempo is 160 bpm, and the third tempo is 175 bpm. Other tempos arepossible.

Part of adapting the melody for a tempo includes preparing accompanyingparts (operations 606, 610, and 614). As discussed above, examples ofcomponents include: strings, woodwinds, horns (also termed brassinstruments), percussion, drums, vocals, etc. Each component can haveone or more sub-components. For example, horns may include trumpet,trombone, French horn, tuba, etc.

Considerations for adapting the parts to the different tempos include,for example, pitch, speed, consistency across song versions, and whethersomething will sound rushed or cluttered.

After one or more song versions are prepared in example method 600, thena plurality of versions are recorded at various tempos (operation 616).In embodiments, performances of the first song version 301 are recordedat 140 bpm, 145 bpm, 150 bpm, and 155 bpm; performances of the secondsong version 302 are recorded at 160 bpm, 165 bpm and 170 bpm; andperformances of the third song version 301 are recorded at 175 bpm, 180bpm, 185 bpm and 190 bpm. Other performances at various tempos arepossible.

The recordings can be a live recording of a musician or group ofmusicians. The recordings can also be a recording ofelectronically-generated music, such as a synthesizer, drum machine,etc. These recordings can be stored on a media server or locally on amedia playback device. In embodiments, each recording at a particulartempo is stored as one file or as a plurality of files where each filecorresponds to a chapter in the recording.

FIG. 7 illustrates an example cadence-acquiring device 160. In theembodiment illustrated in FIG. 7, the cadence-acquiring device 160operates to determine a cadence associated with a user based on movementof the media-playback device 102. In this example, the cadence-acquiringdevice 160 includes accelerometer set 270 and cadence-determinationengine 272.

The accelerometer set 270 includes at least one accelerometer. Anaccelerometer is a device that is used to measure acceleration,including gravitational acceleration. In some embodiments, anaccelerometer measures acceleration in a single direction. In otherembodiments, an accelerometer measures acceleration in more than onedirection, such as in three directions. In some embodiments, theorientation of an accelerometer (and therefore the orientation of themedia-playback device 102) is inferred by comparing the measureddirection and magnitude of acceleration to an expected direction andmagnitude of gravitational acceleration. Additionally, in someembodiments, the motion of the accelerometers is inferred from one ormore measured acceleration values.

In the example shown, the accelerometer set 270 includes threeaccelerometers: an X accelerometer 274, a Y accelerometer 276, and a Zaccelerometer 278. In this example, the X accelerometer 274 operates tomeasure acceleration in a horizontal direction relative to themedia-playback device 102. Similarly, in this example, the Yaccelerometer 276 operates to measure acceleration in a verticaldirection relative to the media-playback device 102. Similarly, in thisexample, the Z accelerometer 278 operates to measure acceleration in afront-to-back direction relative to the media-playback device 102. Inother embodiments, the accelerometer set 270 includes threeaccelerometers that each operate to measure acceleration in threeorthogonal directions (i.e., each of the three directions is pairwiseperpendicular to the other two directions). In this manner, theaccelerometer set 270 operates to determine acceleration inthree-dimensional space.

The cadence-determination engine 272 operates to determine a cadencebased at least in part on the measurements from the accelerometer set270. An example method of determining cadence is illustrated anddescribed with respect to at least FIG. 8.

However, as noted above, some embodiments of the cadence-acquiringdevice 160 do not include the accelerometer set 270 or thecadence-determination engine 272. In these embodiments, thecadence-acquiring device 160 may operate to receive a cadence value overa network from an external device or to receive a user inputrepresenting a cadence value.

FIG. 8 illustrates an example method 820 of determining cadenceperformed by some embodiments of the cadence-determination engine 272using the accelerometer set 270.

At operation 822, a series of measurements is captured from one or moreaccelerometers of the accelerometer set 270. For purposes of thisexample, the method 820 will be described when measurements are capturedfrom a set of three orthogonally-oriented accelerometers. However, otherembodiments capture measurements from different numbers and differentconfigurations of accelerometers.

In at least some embodiments, the measurements are captured at a samplerate of 50 Hz. In other embodiments, the measurements are captured at adifferent sample rate such as a sample rate in the range of 20-200 Hz.Generally, with higher sample rates there will be less error incalculating the cadence. Other embodiments may use different samplerates, including variable sample rates, as well. In at least someembodiments, the captured samples from each accelerometer are stored asa separate series of data points.

In some embodiments, the captured measurements are amplified. Forexample, the acceleration measurements may be quite small when a userplaces the media-playback device 102 on a treadmill rather than holdingit. By amplifying the measurements, the media-playback device 102operates to sense a cadence from smaller vibrations transmitted throughthe treadmill. In some embodiments, the captured measurements areamplified if none of the signals from any of the accelerometers exceed apre-defined threshold for a specific period of time. Furthermore, someembodiments operate to amplify the captured measurements if thelocation-determining device 150 indicates that the user is indoors orstationary.

At operation 824, the series of measurements are filtered based onfrequency to generate filtered signals. For example, in someembodiments, each series is filtered with a band-pass filter such as aband-pass filter comprising third-order Butterworth filters.Beneficially, Butterworth filters provide a generally flat frequencyresponse and thus allows for reliable energy estimation of the filteredsignal. Furthermore, a third-order Butterworth filter provides a steepenough response to discard/attenuate signals outside of the desiredregion. Other embodiments, however, use other types of band-passfilters. For example, some embodiments use a fifth-order Butterworthfilter. In some embodiments, the band-pass filter is tuned to pass theportion of the signal in the series that is likely to correspond torunning (e.g., having a frequency of 140-200 steps per minute). Forexample, the band-pass filter may discard frequencies below 140 stepsper minutes (e.g., walking, holding the media-playback device 102, etc.)and above 200 steps per minute (e.g., vibrations).

At operation 826, the filtered signals are analyzed to determine theperiod of oscillation of the repetitive motion. FIGS. 9 and 10, whichare discussed below, illustrate samples from an example signal andcorresponding periods of repetitive motion. FIG. 9 shows an exampleseries of filtered sample measurements M from an accelerometer capturedover one second. FIG. 10 shows the same series of filtered samplemeasurements M with additional annotations to identify portions of thesignal that are used in analyzing the periodicity of the repetitivemotion. In some embodiments, each of the signals captured (i.e., thesamples from each of the accelerometers in the accelerometer set) areanalyzed to determine the period of oscillation of the repetitivemotion. In other embodiments, the period of oscillation for therepetitive motion of only a single signal that has been identified ascorresponding to the cadence (e.g., as described in operation 828, whichis performed before operation 826 in at least some embodiments) isdetermined.

In some embodiments, the period of repetitive motion is estimated byanalyzing the filtered signals to identify (or approximate) zerocrossings of the signal. In some embodiments, the zero crossings of thesignal are approximated by linearly interpolating between two adjacentsamples that are on opposite sides of zero. In FIG. 10, five exampleapproximated zero crossings are shown as zero crossings X₁-X₅.Additionally, in some embodiments, minima and maxima are also identified(or approximated) for each oscillation. In some embodiments, a parabolicapproximation is used to approximate the minima and maxima of eachoscillation. Other embodiments may use the value of a local minimum ormaximum sample point. In FIG. 7, the maxima (peaks) are shown as maximaP₁-P₃ and the minima (valleys) are shown as minima V₁-V₃.

In some embodiments, the period of the repetitive motion is thenestimated by measuring the distance between equivalent points inadjacent oscillations. For example, in some embodiments, the period isestimated by calculating the distance between adjacent wave maxima(e.g., in FIG. 10, width W₁ between the maxima P₁ and the maxima P₂).Similarly, the period can be estimated by calculating the distancebetween adjacent falling zero crossings (e.g., in FIG. 10, width W₂between the zero crossing X₁ and the zero crossing X₃) and betweenadjacent rising zero crossings (e.g., in FIG. 10, width W₄ between thezero crossing X₂ and the zero crossing X₄). Additionally, the period canbe estimated by calculating the distance between adjacent wave minima(e.g., in FIG. 10, the width W₃ between minima V₁ and minima V₂). Inthis manner, the width of a period of a single oscillation is measuredfour times, with the measurements being offset from each other byquarter oscillations.

In some embodiments, during operation 826, a single measurement of theperiod of oscillation for each of the signals (e.g., from each of theaccelerometers) is calculated and stored. In some embodiments, thissingle measurement is added to a First-In-First-Out buffer that operatesas a circular buffer for storing a predetermined number of measurements.As operation 826 is repeated, the FIFO buffer fills up withmeasurements. When the FIFO buffer is full, new measurements replace theoldest measurement in the FIFO buffer. In this manner, the FIFO bufferoperates to store a predetermined number of the most recent measurementsof the period of oscillation. Some embodiments include multiple FIFObuffers and each of the multiple FIFO buffers is configured to storemeasurements determined from a different accelerometer. However, asnoted above, in some embodiments, measurements are only determined for asingle signal. In these embodiments, a single FIFO buffer may be used tostore the measurements from the signal that has been identified ascorresponding to cadence.

In at least some embodiments, one or more FIFO buffers are configured toeach store twenty-four measurements. Because these width measurementsare calculated at every quarter step, twenty-four measurements arecaptured across approximately six steps (which takes two seconds at anexample running cadence of 180 steps per minute). Because the FIFOqueues are updated based upon oscillations occurring in the filteredsignals in some embodiments, if the user stops running and stands still,the FIFO buffer will not be updated (and beneficially the calculatedcadence will not be impacted by the stop).

In some embodiments, the measurements stored in the FIFO buffer orbuffers are converted to a log base 2 scale. Beneficially, when themeasurements are converted to a log base 2 scale, the measurementsremain linear across a range of cadence values.

At operation 828, a signal corresponding to the cadence is identified.In some embodiments, the signal corresponding to the cadence is a signalfrom at least one of the accelerometers that is most likely correlatedwith cadence. Because the orientation of the media-playback device 102relative to the user U may not be fixed (e.g., when the media-playbackdevice 102 is a smartphone or other mobile device), some embodimentsanalyze the signals captured by the various accelerometers to determinewhich of the accelerometers is oriented to detect movement in thedirection of the repetitive motion at a given time. In otherembodiments, a signal corresponding to the direction of relevantmovement may be identified by combining the signals captured by multipleof the accelerometers.

In some embodiments, the signal corresponding to the direction ofrelevant movement is identified based on identifying the filteredaccelerometer signal having the highest energy. In some embodiments, theenergy of each of the filtered signals is calculated by rectifying thefiltered signal and convoluting the rectified signal with a Hanningwindow of fifty samples (i.e., one second worth of samples at fifty Hz).Other embodiments use a number of samples selected from the range 10-100samples. In some embodiments, other techniques are used to calculate theenergy of the filtered signals.

In some embodiments, the highest energy signal is determined after eachsample is recorded. In other embodiments, the highest energy signal isdetermined at a different interval. Further, in at least someembodiments, the identity of the highest energy signal is tracked (e.g.,after every sample or every tenth sample) so that the identity of thehighest-energy signal (and therefore the direction of the repetitivemovement) can be updated if necessary. Beneficially, by tracking thehighest energy signal, changes in the orientation of the media-playbackdevice 102 will not interfere with identifying the accelerometerassociated with the direction of the repetitive movement. In someembodiments, a signal corresponding to the cadence is identified bycombining portions of multiple filtered series from differentaccelerometers to include the data from the series having the highestenergy over each time interval.

In other embodiments, other methods of determining the direction ofrelative movement are used. For example, if the orientation of themedia-playback device 102 relative to the user U is known or can beinferred, the signal from a particular accelerometer may be identifiedas corresponding to the expected direction of relevant motion based onthe direction of movement to which the particular accelerometer issensitive (which can be inferred from the orientation of themedia-playback device 102 relative to the user). As an example, if themedia-playback device 102 is oriented in an upright position, it can beinferred that that the Y-accelerometer 276 will be sensitive to verticalmovement such as would be expected from running. In this example, thesignal from the Y-accelerometer 276 is used in some embodiments.

At operation 830, a first aggregate value corresponding to the period ofthe oscillation over a first duration is calculated. In someembodiments, the first duration is based on a predetermined number ofoscillations, such as six oscillations. Other embodiments have a firstduration based on a different predetermined number of oscillations suchas 4-10 oscillations. In other embodiments, the first durationcorresponds to a predetermined time period such as 2-10 seconds.

In some embodiments, the first aggregate value is calculated byaveraging multiple estimated widths of the period of oscillation. Forexample, in some embodiments, twenty-four estimated width valuescaptured every quarter oscillation (e.g., the values stored in the FIFObuffer described at least with respect to operation 826) are averaged togenerate the first aggregate value. In some embodiment, the FIFO bufferis updated with a new value every quarter oscillation and the firstaggregate value is also recalculated every quarter oscillation using theupdated values in the FIFO buffer. In some embodiments, the FIFO bufferis pre-populated with measurements that correspond to a typical cadenceat the start of method 820 so that a reasonable first aggregate valuemay be calculated before enough measurements have been captured to fullyfill the FIFO buffer. In some embodiments, the typical cadence valueused to generate values to prepopulate the FIFO buffer is 165 steps perminute. In other embodiments, the typical cadence is calculated based onhistoric cadence information associated with the user (such as cadencedata captured from previous similar activities performed by the user).Because the first aggregate value is based on averaging multiplemeasurements, in at least some embodiments, the aggregate value is notsignificantly affected by intermittent sampling errors or minor, shortvariations in cadence.

Furthermore, in some embodiments, a series of first aggregate values isgenerated as additional measurements are captured. In some embodiments,each of the values in the series of first aggregate values correspond tothe period of oscillation at different time intervals over which theseries of measurements span. In some embodiments, a first aggregatevalue is generated and included in the series after every quarteroscillation. In other embodiments, the first aggregate value isgenerated at a different frequency such as once every oscillation, onceevery second oscillation, etc.

At operation 832, a second aggregate value is calculated based onsmoothing the first aggregate value. In some embodiments, the secondaggregate value is updated (or re-calculated) when the first aggregatevalue is updated. In some embodiments, the second aggregate value iscalculated using equation 1 shown below:y(i)=y(i−1)+α×(x(i)−y(i−1))  (1)

where

-   -   y(i) represents the currently calculated value for the second        aggregate value;    -   y(i−1) represents the previously calculated value for the second        aggregate value;    -   x(i) represents the most recently calculated value for the first        aggregate value (e.g., as calculated by operation 830); and    -   α is a smoothing coefficient.        In some embodiments, the smoothing coefficient α is 0.07. In        other embodiments, the smoothing coefficient α is a value        selected from the range 0.01-0.25. In yet other embodiments, the        smoothing coefficient α is a value selected from the range        0.01-0.99. The smoothing coefficient α is related to the sample        rate; accordingly, in some embodiments with higher sample rates,        lower values are used for the smoothing coefficient α. The        smoothing coefficient α causes the second aggregate value to        change more slowly than the first aggregate value changes in        response to changes in cadence. In some embodiments, the second        aggregate value is initially set to a value that corresponds to        a cadence that is slightly lower than would be expected for the        activity. For example, in some embodiments that relate to        running, the second aggregate value is initially set to a value        corresponding to a cadence of 140 steps per minute. In other        embodiments, the second aggregate value is initially set to a        value that is twenty-five steps per minute less than the user's        historic average cadence for the activity.

In at least some embodiments, other equations or techniques are used tosmooth the second aggregate value. Embodiments are possible using anytechnique for smoothing the second aggregate value in which a previouslycomputed value for the second aggregate value is used in computing anupdated value for the second aggregate value.

Like the first aggregate value, in some embodiments, a series of secondaggregate values is generated as additional measurements are captured.In some embodiments, each of the values in the series of secondaggregate values correspond to a smoothed first aggregate value fordifferent time intervals over which the series of measurements span.Also like the series of first aggregate values, in various embodiments,the values in the series of second aggregate values are generated atvarious frequencies such as after every quarter oscillation, after everyoscillation, after every other oscillation, etc.

At operation 834, it is determined whether the first aggregate value andthe second aggregate value satisfy predetermined tolerances. As notedabove, the second aggregate value changes more slowly than the firstaggregate value changes in response to a change in cadence (e.g., whenthe user first starts running, when the runner changes cadence, etc.).Accordingly, in some embodiments, the difference between the firstaggregate value and the second aggregate value indicates whether theuser's cadence has been stable or changing recently.

In some embodiments, the predetermined tolerances include both adifference tolerance and a duration requirement. An example of adifference tolerance is predetermined number of steps per minutedifference between the first aggregate value and the second aggregatevalue (e.g., within two steps per minute, or within a certain durationof time measured on a linear or log base 2 scale, etc.). An example of aduration requirement is a requirement that the first aggregate value andthe second aggregate value satisfy the difference tolerance for apredetermined duration (e.g., the first aggregate value is within twosteps per minute of the second aggregate value for at least two steps).In some embodiments, the predetermined duration is measured in steps,time, or otherwise.

If it is determined that the first aggregate value and the secondaggregate value satisfy predetermined thresholds, the method 820continues to operation 836 where the cadence is determined. If not, themethod 820 continues to operation 838 where additional measurements arecaptured from the accelerometers in the accelerometer set and theprocess repeats starting at operation 824.

At operation 836, a cadence value is determined. In some embodiments,the cadence value is determined based on the second aggregate value. Todetermine a cadence value from the second aggregate value, the secondaggregate value may need to be converted from a duration in log base 2scale to a frequency value. Once the cadence value has been determined,it can be used for many purposes, including selecting appropriate mediacontent items.

In some embodiments, the method 820 is used to both determine an initialcadence and to detect changes in cadence throughout an activity. Asnoted above, to detect an initial cadence, the FIFO buffer or buffersand second aggregate values may be set to certain initial values thatare selected to minimize the number of steps (or time) required toaccurately detect a stable cadence. For example, by populating the FIFObuffer or buffers with values that correspond to an expected (ortypical) cadence value, the first aggregate value calculated byoperation 830 will immediately be close to a value that corresponds tothe user's instantaneous cadence. As another example, initially settingthe second aggregate value to a value that corresponds to a cadence thatis slightly outside of the expected range may prevent falselydetermining a stable cadence before the user has actually reached astable cadence. Instead, a stable cadence will be determined after theuser has performed with a stable cadence for a sufficient time to causethe initially low second aggregate value to converge towards the firstaggregate value. In some embodiments, a stable cadence is detectedwithin ten to fifteen steps.

In some embodiments, a third aggregate value is calculated in a mannersimilar to the calculation of the second aggregate value (as describedabove with respect to operation 832). The third aggregate value may beused to determine when the user has changed cadence after an initialcadence has been determined. In some embodiments, the third aggregatevalue represents a smoothing of the second aggregate value. In thismanner, the third aggregate value trails the second aggregate value andtakes a longer time to react to changes in cadence. Additionally, insome embodiments, when the third aggregate value and the secondaggregate value are within a predetermined difference threshold of eachother for a predetermined duration threshold it is determined that thedetected cadence value has stabilized. If the detected cadence value hasstabilized at a value that is different from the previously determinedcadence by a sufficient threshold a new cadence value is determined (andmay be used in media content selection or otherwise). Examples ofsufficient thresholds include two steps per minute, five steps perminute, or ten steps per minute. In some embodiments, the sufficientthreshold is a value selected from the range 1-15 steps per minute.

In at least some embodiments, the third aggregate value is calculatedusing an equation that is similar to equation 1 (described above withrespect to operation 832) such as equation 2 shown below:z(i)=z(i−1)+β×(y(i)−z(i−1))  (2)

where

-   -   z(i) represents the currently calculated value for the third        aggregate value;    -   z(i−1) represents the previously calculated value for the third        aggregate value;    -   y(i) represents the most recently calculated value for the        second aggregate value (e.g., as calculated by operation 832);        and    -   β is a second smoothing coefficient.

In some embodiments, the second smoothing coefficient β is 0.02. Inother embodiments, the second smoothing coefficient β is a valueselected from the range 0.001-0.1. In yet other embodiments, thesmoothing coefficient α is a value selected from the range 0.001-0.99.Like the smoothing coefficient α, the smoothing coefficient β is relatedto the sample rate; accordingly, in some embodiments with higher samplerates, lower values are used for the smoothing coefficient β. The secondsmoothing coefficient β causes the third aggregate value to change evenmore slowly than the second aggregate value changes in response tochanges in cadence. As mentioned above with respect to the secondaggregate value, the third aggregate value is also calculated usingother smoothing equations in some embodiments.

Like the first aggregate value and the second aggregate value, in someembodiments, a series of third aggregate values is generated. The valuesin the series of third aggregate values correspond to smoothed secondaggregate values over various intervals over which the series ofmeasurements span. The values in the series of third aggregate valuesmay be generated at the same frequency as the values in the series ofsecond aggregate values or at a different frequency. Although theexamples described herein use accelerometers, in other embodiments othertypes of movement-determining devices are used. A movement-determiningdevice is a device that operates to capture measurements related tomovement of the media-playback device. An accelerometer is an example ofa movement-determining device.

In embodiments, the media playback device can play a song or songversion that is created dynamically rather than playing a pre-recordedsong or song version. That is, each of one or more parts in a song arecreated real-time and are based on one or more rules.

In embodiments, the media-playback device 102 includes an altimeter orpressure sensor that can detect changes in height. In these embodiments,the media-playback device 102 begins playback of one or more musicalparts. Based on one or more rules, the parts vary depending upon auser's cadence, location, change in altitude, etc. For example, thedrums part of a song can vary in intensity, complexity, syncopation,etc., at different cadences. As the user maintains the cadence, or asthe cadence changes, other parts are added, such as strings,synthesizer, horns, vocals, etc. The tempo and intensity of the song canalso change. If the user's altitude changes, by ascending stairs or ahill, for example, additional components are added or eliminated, or theparts could crescendo. In this way, the song changes dynamicallydepending on the user's cadence and activity.

As noted previously, although many of the examples provided above aredescribed with respect to running, other embodiments relate to otherrepetitive motion activities as well such as cycling, swimming, androwing.

The various embodiments described above are provided by way ofillustration only and should not be construed to limit the claimsattached hereto. Those skilled in the art will readily recognize variousmodifications and changes that may be made without following the exampleembodiments and applications illustrated and described herein, andwithout departing from the true spirit and scope of the followingclaims.

The invention claimed is:
 1. A computer readable data storage devicestoring instructions that, when executed by at least one processingdevice, cause a media-playback device to: acquire a first cadence;initiate playback of a first song version selected from a plurality ofrelated song versions, wherein the selection of the first song versionis based on the first cadence; and wherein the first song version isdivided into a plurality of chapters; determine a location of playbackfor the first song version including a chapter number of a chapter ofthe plurality of chapters, and a percentage of the chapter, played;acquire a second cadence; and initiate playback of a second song versionselected from the plurality of related song versions, wherein theselection of the second song version is based on the second cadence;wherein the second song version is divided into the plurality ofchapters; wherein playback of the second song version begins at atransition position in the second song version that corresponds to thelocation of playback for the first song version; wherein the first songversion and the second song version share at least one characteristic;and wherein each of the plurality of related song versions is differentfrom each of the other plurality of related song versions in at leastone characteristic.
 2. The computer readable data storage device ofclaim 1, wherein the playback of the second song version is faded in atthe same time the playback of the first song version is faded out. 3.The computer readable data storage device of claim 1, wherein the firstsong version and the second song version share at least a melody; andwherein a tempo of the first song version and a tempo of the second songversion are different.
 4. The computer readable data storage device ofclaim 3, wherein a tempo of the first song version is at least about 5beats per minute different than a tempo of the second song version. 5.The computer readable data storage device of claim 4, wherein the tempoof the first song version corresponds to the first cadence; and whereinthe tempo of the second song version corresponds to the second cadence.6. The computer readable data storage device of claim 3, furthercomprising instructions that, when executed by the at least oneprocessing device, cause the media-playback device to: request a streamof the first song version from a media server; and request a stream ofthe second song version from the media server.
 7. A method fortransitioning from a first song version to a second song version, themethod comprising: acquiring a first cadence; selecting a first songversion that corresponds to the first cadence, the first song versionbeing divided into a plurality of chapters; streaming the first songversion; determining a location of playback for the first song versionincluding a chapter number of a chapter of the plurality of chapters,and a percentage of the chapter, played; acquiring a second cadence;selecting a second song version that corresponds to the second cadence,the second song version being divided into the plurality of chapters;and streaming the second song version beginning at a transition positionin the second song version that corresponds to the location of playbackfor the first song version.
 8. The method of claim 7, wherein each ofthe plurality of chapters is between about 2 minutes and about 12minutes.
 9. The method of claim 7, wherein the first song version isfaded out at the same time that the second song version is faded in. 10.The method of claim 9, wherein the first song version and the secondsong version are faded in and faded out for about 2 seconds to about 5seconds.
 11. The method of claim 7, wherein a tempo of the first songversion is at least about 5 beats per minute different from a tempo ofthe second song version.
 12. A media server, comprising: a databaseincluding at least one computer readable data storage device,comprising: a plurality of song versions, wherein each of the pluralityof song versions has a different tempo than each of the other songversions; wherein the at least one computer readable data storage devicehaving instructions stored thereon which, when executed by at least oneprocessing device, cause the media server to: receive a first request tobegin streaming a first song version, where the first song version has afirst tempo; enable streaming of a first song version, the first songversion being divided into a plurality of chapters; receive a secondrequest to begin streaming a second song version, wherein the secondsong version has a second tempo and the second song version beingdivided into the plurality of chapters; wherein the second requestincludes a location of playback for the second song version, thelocation of playback including a chapter number of a chapter of theplurality of chapters, and a percentage of the chapter, played; andwherein streaming the second song version begins at the location ofplayback that corresponds to the location of playback for the first songversion; and enable streaming of the second song version, wherein thefirst tempo and the second tempo are different by at least about 5 beatsper minute.
 13. The media server of claim 12, wherein the at least onecomputer readable data storage device further includes instructionsstored thereon which, when executed by at least one processing device,cause the media server to: stop streaming the first song version after apredetermined time of streaming the second song version.
 14. The mediaserver of claim 12, wherein the first song version and the second songversion have a same melody.